Dual fuse with indicator



March 23,1937. L, A KAQFFMAN 2,074,400

DUAL FUSE WITH INDIJATOR Filed April 24, 1935 Patented Mar.` `1937 -V`lcarrito srrii'rlts 2,074,400 DUAL Fusi: wim mnrca'ron Leroy A.Kauffman, Washington, D. C., assignor indicating lFuse ManufacturingCorporation,

Washington, D. C., a corporation oi Delaware Application April 24,1935,serial No. v118,040

' y' s claims. (ci. zoo-121) ing parts are designated lby similarreference The present invention `relates 'to circuit breakers for -theprotection ci electrical circuits (employing a fusible element)Whichbecomes blown or ruptured'when a short circuit or overload occursin ther electrical circuit lhaving amongst its' principal objects theprovision of an automatically controlled switch connected in sey rieswiththe-vfusible element which will function beforethe fusible elementwhen a 'slight overload occurs to break the electrical circuit andcontinue to intermittently and momentarily reestablish the currentshould such overload continue over a period of time, thereby maintainingthe circuit in substantially continuously broken condition and whichwill again close'the circuit'when -such overload is removed therebyincreasing the ufe of the fusible element.

A further object of the invention. is to provide afuse with two thermalcontrol circuit breakers ci different amperage, the circuit breakerhaving the lower value being adaptedl,to automatically open and closethe electrical-circuit and the circuit breaker having the greater` valueadapted to permanently open the electrical circuit when blown orruptured'.

A still further object ofthe invention is lto provide a fuse comprisingtwo' thermal control cir--` cuit breakers connected in' series and anindicator connected in parallel therewith, whereby when either circuitbreaker is opened, said indicator will announce or signal thebrokencondition of the electrical circuit to which the fuse 'is l applied., 1A

" Another object ot the invention is to provide a fuse comprising aunitary structure having a plurality of circuit breakers housed thereinand connected in series with the contact terminals of the fuse and anindicator connected to the terminals of the fuses, but arranged inparallely Withthe circuit breakers for indicating the ruptured conditionof either circuit breaker,

Other objects of the inventionwill be in part obvious and inpar'trpointed out hereinafter.

In order that the invention and its mode of op- 'e 55 panyingA drawing,wherein like and correspond through l K characters throughout theseveral views, I have Y herein shown a fuse of the plug type'consistingoi' a casing molded from a suitable insulating material to provide anupper section I and a lower or detachable section l The upper section?!has attached thereto a threaded contact shell 3 capable of being ttedwithin a standard scket of the ordinary cut-out block and detachablyfitted within this shell 3 is the lower section 2. q The upper section lhas formed therein a centrai recess in which is arranged an indicator s,

herein shown as a miniature glow lamp 4. Terminal 5 of this lamp isconnected to the shell 3 through a resistor 6. The resistor as hereinshown is formed from a plastic composition containing carbon andglycerine and is positioned.

Within a recess formed within the section l of the gcasing as is betterillustrated in Figure l'. The -wother terminal i' of the lamp 4 isattached .to ab tion i ofthe casing.

rivet 8 secured Vwithin the lower end of the sec- The lower section 2 ofthe casing has formed l thereinran annular recess so that when the saineis connected to theupper section l, a fuse compertinent 9 is formed. Arivet iii forming a contact terminal oi the fuse is mounted within thelowersection of the casing. The fuse link il is carried by a holder l2and when placed within the ruse compartments, one end of this link ilcontacts the rivets B and it; thereby completing a connection betweenthe terminal i of the lamp indicator and the contact rivet iii.

The automatically controlledxcircuit breaker comprises la switch havinga movable blade i3 and a stationary contact it. To provide thisstationarycontact, i' form a metallic copper strip in the shape as isbetter shown in Figure 3 in orderthat one end i5. may project within thefuse, compartment 9 and have contact with one end of the fuse link iiwhereas, -its opposite end projects within the chamber i6 and forms theriveted thereto asat l1, an arm l8- made from a suitable bimetallicmaterial and the lower end oi this arm i8 `is connected with andsupported Vby ,an extension i9 which latter extends through `thefusefcasing and has Contact with the upper end of the shell, 3. Theupper end of the chamcontact it. The upper end of the blade i3 has'.A

ber I8 is closed by means of a plug 2,0a'nd the A lower face ofy thisplug is provided with a recess y l2l in which mayloscillate and pivotthe upper connected ends Yil' of the arm 18 and switch blade I3. Theouter face 22 of this plug!!! may have suitable markings thereon todeste the ratings in amperes or the fuse whereas. the outer face 23 ofthe fuse casing may have the required markings such as thetradei-M k,nome f menufacturer and voltage oi the fuse.

2t are formed with the outer edge of the section i of the fuse casingthereby providing a ha grip for turning the fuse, into and out of thecut=out base socket to which the fuse is to be applied.

lo From the foregoing, it is obvious vthat the clisg-a h@ me link H Mdthe cuit breaker comp circuit breaker comprising e switch blade i8 areconnected in series with the termils i@ 25 preciabie diminution oi theirtheo-nenible properties and yet form a good conductor predetermining thepebie maximum current how, but is adapted to automatically respond tothe heat generated by excess temperatures by fien- 30 ing to a circuit:its ition. arm i8 having e. thickness and width adapg it to carry orconduct a ww perego, but an amperage of a lower value than that oi themaximum value of the fuse ii will, when a slight 35 overload occurs inthe electrical circuit to which vit is applied by the 4heat generated,des the arm i8 so as to cause it to'wilr-vr the blade i3 i'rom thecontact it before the fuse link ii becomes blown or rub and therebybreak the v 4o circuit. As the arm it cools, it will automaticallyreturn to' its normal position to again cause the blade i3 to engage thecontact it for ablishl ing the circuit, but should the overloadcontinue, the arm i8 will maintainthe circuit in subs 45 tially acontinuous broken condition until the overload is removed. `However,.should the over load or short circuit ca an '..r c. .s to a .valuegreaterthan the the fuse link ii, the latter will :f 50 to the heat sogenerated and permanently open the circuit until such time as a new fuselink is substituted therefor.

4 The plug 2d when piacedin position will exert 'a pressure upon the armlo and blade it so.` as 55 to flex the same in their normal tions as isshownin full lines in 1li dfwhereby the blade i3 will be retained incontact with terminal i4. en the hat is generated by the overloadoccurring in thefclectrlcal circuit, the

shown in dotted lines in Figure i thereby drawing the blade it out oiengagement with the contact it. The upper connectedends il or-the arm itand blade iB' are fulorumed within the recess 2l oi the plugl@ in ,aucha manner as to permit a slight variation inftheiriulcnnn point andtherebyrcause-ithe blade to snap out o! arm I8 will contract or e theposition as .of said compartment,

ruse plug, so that'st overloads that occur in `an electrical circuit maybe taken care oi with- `out rupturing the fusible elementn but in the'event a short circuit or exve overload occurs, the fuse link willfunction inthe usual manner and the lamp 4 will signal or indicate theopened condition of either circuit breaker.

Maniftly, the construction herein shown is capable of considerablemodication and such modifications as come' within the scope of my cl, Iconsider within the spirit ci my inven tion.

I claim:

1. A fuse comprising a body. a center contact. a shell constituting aside contact. a thermo-responsive switch housed in said body and havinga stationary section and a movable section, a u'se link connecting thestationary section with the center contact, a thermos-responsive stripextending longitudinally of the movable section and having one endsecured to an end of the movable section and being normally bowed in onedirection to support the movable section in position to engage thestationary section, s for electrically connect the other end of thethermo-responsive strip with said shell. the strip when bowed in anopposite direction in response to change in thermal conditions supmrtingthe movable section out of contact with the stationary section, a pocketbeing formed in said body and open at one end, a glow lamp indicator insaid pocket visible through the openend thereof, a resistor connected inseries with said lamp, and means for connecting said glow lampl and theresistor in series with the center contact and the side contact but inparallel with said thermoresponsive switch and the fuse link whereby theinoperative position ci' the thema-responsive switch or the fuse linkmay be visibly indicated.

2. A plug fuse comprising a casing having aplurality of compartmentsindividually separated from one another and located within said casing.a fuse link arranged within one of said compartments, athermo-responsive switch arranged within one of the other oi saidcompartments, a lamp indicator nged within the remaining one'of saidcompartments, a central contact secured to said casing, a screw shellcontact secured to said casing, means arranged within said casing forconnecting said theme-responsive switch and ruse element in series withsaid `central contact and said screw shell contact and l means arrangedwithin said casing for electrically connecting sald lp indicator withsaid central contact and said screw shell contact wherebythe inoperativeposition of either said fuse linkv or said thermo-responsive switch maybe visibly indicated.

3.a fuse unit comp a casing, a pairof spaced contact terminals carriedby said casing, said casing having an opened end compartment formedtherein dening intercommunicating inner and outer chamber, a circuitbreaker 'arrangedwithinsaid o .tf-:Mt- -fand including a stationarycontact in the inner 'and electrically connected to one contact terminaland extending into the outer chamber and a movable contact in the 'outerchamber electrically connected with the other contact terminal, aplug'secured within and closing the'opened vend Seid plus ensasins themoveableccntact of said circuit breaker .for normally@ holding the samein engagement with the stationary contact.

v i l 4. A plug fuse comprising a casing, a central contact terminal, ascrew shell terminal, said casing having an opened end compartmentformed therein, a thermo-responsive switch arranged within saidcompartment and being electrically connected to said central contactterminal and said screw shell contact terminal, said thermoresponsiveswitch comprising a xed blade and a movable blade, a plug for closingthe opened end of said compartment and engaging said movable blade ofsaid thermo-responsive switch for normally retaining the movable bladein contact with the xed blade of said thermo-responsive switch and saidplug having a recess formed therein providing avariable fulcrum pointfor the movable blade oi said thermo-responsive switch.

5. A plug fuse comprising a casing. a central contact terminal, a screwshell contact terminal, a thermo-responsive switch arranged within saidcasing, saidthermo-responsive switch comprising a xed blade and amovable blade, means for connecting an end of said xed blade to saidcentral contact, an abutment having a seat shiftably receiving the otherend of saidA movable blade, a bimetallic arm for normally retaining saidmovable blade incontact with said xed blade having one end ilxedlyconnected to said movable blade and holding the said end of the movableblade in the seat of said abutment and means for connecting the oppositeend of said arm to said screw shell contact terminal. 6. A plug fusecomprising a body having upper and lower sections, a shell connectingsaid sections and constituting a side terminaba c nter terminalextending through the lower tion axially thereof, the lower sectionbeing formed with a fuse chamber surrounding the center terminal andVopen at its'upper end, the upper section being formed with an axiallyextendingl pocket open at its upper end and with a i. longitudinallyextending switch chamber spaced cator in said pocket having terminalsconnected with the resistor and the stud terminal; a thermoresponsiveswitch havingfa stationary member in the fuse chamber engagingthe fuseand a movable member in the switch chamber, a bimetallic member holdingthe movable member in contact with the stationary member and connectedto the shell, and a plug closing the switch chamber and constituting afulcrum for the movable member.

7. A plug fuse comprising a body having upper and lower sections, ashell connecting said sections and constituting an external sideterminal, the upper section being formed with a pocket, a contact studsecured through the bottom of said pocket, a center terminal carried bythe .'.Jwer section under said stud, a fuse having one end clampedbetween the stud and center terminal, a resistor between the shell andpocket, a glow'lamp in said pocket having terminals connected with theresistor and the contact stud,

' said upper section being also formed with a switch chamber having areduced passage leading from its lower end and a side passage, a plugclosing the outer end of the switch chamber, a stationary switch memberbearing against the under face of ing of a bimetallic strip extendinglongitudinally in the switch chamberwith its upper end bearing againstsaid plug and its lower end provided with a foot extending through theside passage yand secured to said shell, and an arm extending sectionand engaging said fuse link, a side con' tact, the upper section being.formed with an open pocket-and with a. switch chamber, a'plug closingthe switch chamber, a glow lamp in said pocket, a resistor in serieswith said lamp, the resistor and lamp being in series vwith the centercontact,

fuse link and the side contact, a, stationary contact resting upon saidfuse link between the upper and lower sections and having an armextending Iinto the lower endportion of the switch chamber, a bowedbimetallic strip in the switch chamber v having its lower end connectedto the side contact and its upper end in shiftable engagement with saidplug, and an arm Aextending downwardly from the upper portion of thebimetallic strip with its lower portion normally in engagement with thearm of the stationary contact.

LEROY A. KAUFFMAN.

